390 BOTANICAL GAZETTE [DECEMBER 
and in the solvents enumerated above. The absorption spectra 
will be found represented in figs. ro—106. 
If to the gelatin, prepared as has been described, a few’ 
grams of glucose, lactose, or similar bodies are added, instead of 
a green, a magnificent blue is obtained, permeating the culture 
medium completely and uniformly. The blue changes in a few 
days to a violet, then to a royal purple, and finally, as the cul- 
ture grows old, the color disappears, the liquefied gelatin acquir- 
ing a brownish red color. Both the violet and the purple are 
dichroic, that is, are red by transmitted light. The liquefaction 
of the gelatin is considerably retarded by glucose, lactose, etc., 
as has been observed with many other species of bacteria. 
The blue soluticn obtained by filtering young glucose-gel- 
atin cultures reacts toward reagents in every way like the blue 
obtained from potatoes, that is, with acids first a violet, then a 
purple, and at last ared results; ammonia also produces a red; 
fixed alkalies give a green, soon fading and leaving a brownish- 
yellow solution which, when shaken with air, becomes first green, 
then blue. The absorption bands given by these solutions will 
be found in figs. ro-16. 
Since it was found that these bands seemed to correspond in 
character, position, and intensity with those given by similarly 
colored or treated solutions of the pigment isolated from pota- 
toes, no attempt has yet been made to isolate the coloring matter 
from gelatin. For the purposes of comparison, the filtered solu- 
tions were diluted with water until the colors given with reagents 
were approximately the same as those obtained with 28" pet 
liter of the purified pigment. 
The spectra of these gelatin solutions need but a fe 
in explanation. A few of the most important have bee 
in order that they may be compared with the similarly 
solutions shown by figs. 7-9. | . 
Fig. 11 gives the absorption spectrum obtained with strongly 
dichroic green solutions. Acetic acid added to such solutions 
causes the change shown by fg. 72. ig. 13 represents - 
appearance seen when the violet solutions from cultures 2 
w words 
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treated 
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